Fireworks – Stacking techniques and fisheye lenses

A quick look today at some photos taken of a wedding fireworks display combining a fisheye lens and post production merging or “stacking” of images. The brief with this assignment was to capture some “ground zero” close-up action whilst still keeping a point of interest – a large tower – in the background.

The fisheye view of fireworks

Once you start taking firework photos you soon realise that half the time you are far too close to them. The two solutions to this are either move further away, or buy a wider angle lens. Moving further away is certainly the cheapest option but there are so many circumstances when this isn’t possible, either due to a confined venue or the risk of losing a good vantage point.

A wide angle lens then becomes one of the firework photographer’s first investments in additional glass. Here there are a further two options: Fisheye or a normal non-fisheye wide angle.

Although I shoot a lot of images with a full frame fisheye lens, I would say that a non-fisheye wide angle has to be the priority. The latter retains the proper perspective and is simply a much wider version of the kit lens. Images will for the most part be non-distorted and the horizon will remain straight. A fisheye lens on the other hand will either create a circular image in the middle of the frame, or will fill the frame but distort the image significantly.

The reason why I have a fisheye lens in my kit bag rather than a “proper” wide angle lens is because I bought it for a specific non-fireworks role, namely to create 360 degree panorama images. That requires the use of a specialist tripod mount and a fisheye lens captures the widest possible area. The images are then merged and straightened out in the panorama software. It was some time before I tried taking fireworks using it and the results were predicatable: Very wide angle but also terribly distorted and “bendy”.

I’ve come to live with the fisheye effect and luckily many fireworks shots disguise the distortion because of the large amounts of black sky or careful placement of the horizon dead-centre. With these shots today however I had to set the camera up quite close to the fireworks and it was impossible to capture both the left hand fireworks and the right hand tower – which is an area covering nearly 150 degrees – without using it. The kit lens at 18mm was nowhere near wide enough. The results as you will see get all the action in, at the expense of a very curved ground and leaning tower on the right.

So lesson number one today: If you want to go beyond the limited wide angle of your kit lens and open up a whole new world with ultra-wide angle shots, avoid a fisheye or full frame fish-eye lens. The fisheye lens is a specialist lens which will distort images. Although it is possible to remove the distortion afterwards, this does degrade the quality of the image.

Stacking fireworks photographs

In my recent article Merging Images I walked through the technique of merging or stacking photographs afterwards to simulate a long exposure shot. For this display in a confined space the technique was all the more important because of the risk of long exposure shots over exposing. By taking lots of short images (8 seconds each) it would be possible to pick from a lot of frames and give much more control over the results.

Another factor with these photographs was smoke. The only position I could set up to get the fireworks and the tower in was downwind of the fireworks. Smoke can ruin shots when it is lit up by brighter fireworks and that was another reason why I decided on short images of 8 seconds rather than, say, 30 seconds each. Finally, with the risk of a lot of smoke around I closed my aperture down to F16 instead of the usual F13 or F11. ISO remained at 100 with a manual white balance selected of “Outdoor” (see the Fireworks White Balance article for help on that).

Remember, stacking images is only possible if the camera remains completely stationary during the shoot. Set it up on a tripod and leave it.

The resulting fireworks photos

Here is the very start of the display. Note how the firers’ portfires (bright green burning tubes used to light fireworks) show up as trails in these images as they walk around, looking like dancing green lightning in some cases. The very bright lights in the photograph are actually fireworks – the blinking strobes used at the start.

Straight away you can see the fisheye distortion of the ground as it bends like a bowl. This image is a composite of five merged images showing a total of about two minutes of display time from the initial strobes through to the opening shell barrage. A number of frames were dropped – the ones containing just the strobes – to bring the exposure down a bit. I also included some frames from the pre-display checks which included the portfire trails.

Combining all the photos from this time sequence without dropping any resulted in a very over exposed image due to the strobes. However that is a good case in point regarding the flexibility given from using more shots each of less time.

In the next image I am cropping in to highlight a firer. The display time is around 40 seconds and is taken from five sequential frames stacked together. One firer is surrounded in his own light show, the other can be seen only by his portfire trail. It starts out on the left at the shell racks and then walks over to the centre. The gap part way along is where the camera finished one 8 second shot and moved to the next. Finally, the portfire trail dips as he lights the next firework!

As a point of interest here is the same sequence zoomed out to show the full frame, including the tower. Note how I have added an extra couple of frames to include some more fireworks (you can spot this by comparing the portfire trails on the right):

This image from the end shows the last shell barrage plus some odd green trails – these are caused by the firers “waving” to the audience at the show’s end!:

To finish this article I’d like to share a fun image of the whole display. Using all 45 images stacked together as a starting point I went through them removing ones which were overexposed. With all the smoke around, the strobes and some set pieces, I had to drop about a dozen frames to get a usable image which wasn’t just a mess of white: